Plaster board



Feb. 14, 1928.

M. K. lARxvlsrRCmG PLASTER BOARD Filed Deo. 12. 1921 Patented Feb. 14, 1928.

MORGAN K. ARMSTRONG,

PATENT oFFicE:

OF WINNETKA, ILLINOIS.

'BLASTER BOARD.

- Application led December This invention relates to improvements in plaster board and consists of the matters hereinafter described and more particularly pointed out in thefappended claims.

The invention is `addressed specifically to a plasterl board of the kind comprising top and bottom covering sheets 'of paper or other fibrous materialV and an interposed body `,of plaster, the main ingredient of i which is gypsum. to which body the covering sheets are adhered by reason of thel adhesive character of the plaster comprising the body.

Plaster board of the kind has been made with the plaster body exposed at the edges, and has also been made withthe edges of the plaster body bound or protected by means of extensions on one ofthe covering sheets, which are turned about said edges and over on top of the opposite side of the board,the extensions-being sealed either under or on top of the edges of the other sheet by means of the plaster material of the body. The object ofthus binding the edges of the sheet is toprovide smooth, square edges for vthe board and also to reinforce the board at the edges and prevent it from breaking when handled or by the action of nails when nailing it in place.`

TheL object of m invention is to provide r a plaster board o the kind with substantially straight, true, square edges, without the necessity of binding theedge by extensions of one of the covering sheets, and at the same time to -provide said board with edges which maybe nailed in position without breaking.v The advantages ofthe nvention4 will'appear as I proceed with my specification.

In the drawings Fi re 1 is a perspective vieu of a width of bbard which mal be cut into two lengths 4of board of the klnd involving my tion.

Figure 2 is akview showing a transverse sectionthrough a board embodying the invention.

Fi res 3 and 4 are detail, sectional views showing modified forms of the edge of the board, to be more `particularly referred to. later. y Referring lnow to the drawings particularly to Figure 2-10 indicates the top invensheet' of a board embodying myinvention,

and 11 indicates the bOttfmq Sheet, 1 2 indi- 12, 1921:.` Serial No. 521,576.

cates the interposed body of plaster ma'- terial which is of a familiar kind, and is made up largely of gypsum. Such a plaster board isi well known to those familiar with the art. 13, 13 indicate strips or bands of a nailing mixture interposed between theltop and` bottom sheets of the plaster board at the edges ofthev board. This nailing mixture may be of an suitable composition comprising ingredie ts' which will harden and which will be of an adhesive character sufficient to become adhered to the overlying parts of the covering sheet of the board, and which will permit a nail to pass through it wit-Hout breaking or disintegrating. Such amixture may be made of tar, sawdust or other fibrous material and clay, whieh yare preferably mixed hot.

In the manufacture of the board, covering sheets 10, 11 ofthe width of the board are used and the` strips o r bands of nailing mixture 13 .are laid 0n the bottom sheet l1 lat the edges of the sheet and the plaster VJbody 12 is spread upon the bottom sheet in the space between said bands 13, both tlie nailing mixture and the plaster body being .applied when in a plastic condition. The top covering sheet is then' applied and adhered by pressurev to the intermediate body of plaster 12 and to the bands 13. In the application of the'pressure to the top `sheet v10 the material of the plastic body 12 and the material of the nailing mixture bands 13r .is forced into .intimate engagement at the proximate edges so that said edges will adhere together, thus providing when the board is finished, a substantially integral body extending between the edges of the board. The outer edges 14, 14 of the nailing mixture bands may be made true and square and flush with the edges of the covering sheets so that whenthe board 1s completed, its edges are smoothand true.

The board may either be made .in the beginning of the desired width, or 1t maybe made of double width as shown m Fig. 1, according to my Patent 1,578,250, March 30, 1926. In said figure the top sheet 10 and the bottom sheet 11al are double the width of the intended board. In the manufacture of the double width board, the nailing mixture bands 13, are providedY at the outer edges of the mam board and a wider nalling mixture band 13b is provided in the middle of the board? Then aber the double width board lmiddle line 15, so that when sawed or cut through the middle, the edges along the line 15 will be similar' to the other edges of` the board.

vAgain the board may be formed without the aforesaid bevel, and with the edges made of t-he saine thickness throughout, as illustrated at 18 in Fiofure And the face 0f the edge may be 'Iat asshown at 18X or it may be made concave as indicated at 19x in Figure 4, thus providing a space between two adjoining boards for a key. When the board is vmade without the bevel, as in Figures 3 and 4, both faces of the board are identical, so that if one face is damaged it may be faced inwardly and the other may be faced outwardly.

I claim as my invention Y 1. A`plaster board comprising a plaster body which is narrower than 'the board to be made, strips of substantial width of a nailing mixture of diferent composition from thatof the plaster body adhered to the lateral edges of said'plaster body, and completing the designed width of said board,

top and bottom coverinvr sheets of paper adhered to said plaster l body and projected beyond the same to include within their limits said strips, and saidtstrips filling the entire depth of the spaces between the over lapping margins of said covering sheets and being adhered thereto.

2. A ,plaster board comprising a main plaster body and nailing mixture strips adhered to the edges of said plaster body and forming the edges of the board, and top and bot-tom covering sheets of paper adhered to said plasterl body and to the said nailing strips, the top covering sheet adjacent the edges of the board being inclined downwardly toward said edges.

3.' A plaster board comprising a plaster' body formed of a core margined by edge strat-as of previously prepared composition having different characteristics than said 4. A plaster board comprising a plaster' of Paris product body having its edges formed of strips of previously prepared hardened reinforcing substance of different composition than the center.

5. A plaster board comprising a plaster of i Paris product body having its exposed edges formed of strips of previously prepared hardened reinforcing and waterproofing substance of different composition than the center, J`said body being disposed between tibrous covering sheets.

In testimony that I claim the foregoing as my'invention, I al'lix my signature, this 8th day of July, A. D. 1921.

` 'MORGAN K. ARMSTRONG. 

